Numerous applications require the determination of the presence or absence of one or more substances in a particular sample. In particular, several applications require that the presence or absence of a material in a fluid sample be detected. Such applications include, for example, determining or monitoring of emissions or liquid effluent from stationary or mobile sources for the presence of one or more substances in the emissions. It would be beneficial to have a sensor for detecting the presence or absence of materials in various samples that is both efficient and relatively inexpensive. Furthermore, such a sensor should be reliable and relatively fast in performing the analysis. Furthermore, many of the applications requiring such sensors are mobile or remote applications that do not have ready access to a power supply that is not a battery or other stored type of power supply. Accordingly, it would also be desirable for sensors in such applications to use relatively low power when performing analysis of the samples.